Actuatable vehicle occupant protection systems are well known in the art. Such protection systems include one or more vehicle crash sensors for detecting the occurrence of a vehicle crash condition. When a vehicle crash condition is detected, the protection system may actuate an inflatable device, such as an air bag, for helping to protect an occupant of the vehicle.
Known vehicle crash sensors include mechanical devices, such as switches, that close in response to deformation of the vehicle. The closure of the mechanical device indicates the occurrence of a vehicle crash condition. Other known vehicle crash sensors are electrical devices, such as an accelerometer. When a processed output of the electrical device crosses a threshold level, a vehicle crash condition is determined.
Vehicle crash sensors for detecting a side impact to a vehicle must have particularly rapid response times as the time period for actuating an inflatable device for the protection of the occupant during a side impact is significantly less than the time period for actuating an inflatable device for the protection of the occupant during a front impact. To help improve the response time of a vehicle crash sensor for sensing side impacts, it is common to locate the vehicle crash sensor at the side of the vehicle, such as on a side pillar or within the door of the vehicle.
Some difficulties arise when the vehicle crash sensor is located within the door of the vehicle. For example, the vehicle crash sensor must be able to sense a side impact, but must be immune to actions such as door slams. Also, a vehicle crash sensor within the door must be immune to low force impacts to the door such as those common when a door is opened into an object.